All posts by jb38
Below are all of jb38's postings, with the most recent are at the bottom of the page.
Gareth: As an engineer who up until recently has been involved with transmission equipment for years, albeit I still am to a certain extent, I am therefore naturally rather interested in this problem, especially the aspect concerning the levels of the strength and quality of the signal prior to the drop out, as well during the actual drop out.
Insomuch, is the signal "strength" seen to fluctuate immediately prior to the drop out, and when the drop out occurs does both the strength and quality vanish? (indicating an RF carrier failure) or is it only the quality that vanishes but with the strength still being indicated at roughly the same level as before? this then inclined to suggest that the signal data is being seriously corrupted by such as a spurious burst of oscillation whereby it cannot be decoded by the receivers, hence a blank screen.
Would appreciate clarification on which of the two aforementioned situations applies.
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Gareth / anthony : Many thanks for the replies, the content of having clarified the issue, insomuch confirming that the signal strength drops to zero when the drop out occurs, and that its "not" one of those cases where a message indicating "no signal" is being triggered by something having affected the quality of the signal, as happens in many devices.
By the way, although having followed all said on the subject by viewers affected by the problem, the issue on continuity of signal strength was raised by a former work colleague who dropped by yesterday evening for a chat, a quick re-check on the aforementioned postings referred to leaving us unsure as to whether the strength was vanishing or not, hence the main reason for requesting clarification on the issue.
Thanks again / jb.
PS: Just noticed MikeP's posting on the subject, although the symptoms of an overly strong signal can indeed result in exactly that said by MikeP, and so by all means try a test by inserting an attenuator in line, but considering the fact that the main BBC B HD transmitter is radiating on 100Kw without any problems having been reported, I very much doubt if COM7 radiating on only 25.7Kw is likely to result in overloading anything.
But though one never knows! as predictions involving RF signal strength is seldom ever really accurate apart from when taken from some test point on the actual transmitter.
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anthony: Yes, intermittent faults are always difficult to cure, but judging by what Gareth and others have reported, including of course yourself, the content of being highly suggestive of intermittent carrier failure, and as such I feel that its only a matter of time before field checks are carried out in various localities around the circumference of the coverage area in order to determine one way or another if the problem is being caused by a defect on the mast, (nasty!!) as its rather obvious that nothing abnormal is showing up on the TX indicator meters otherwise the problem would have been rectified by now.
One thing I forgot to ask being, on average how many times in an evenings viewing is this drop out problem liable to be experienced?
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rosey : Many parts of NN5 area are, and always have been, notorious for suffering from variable levels of reception from the Sandy Transmitter basically due to the signal path from Sandy's mast not having a clear line of sight to the area, this then resulting in the signal being vulnerable to the effects of seasonal changes to the surface of the terrain, as well as to a lesser degree, problems caused by atmospheric changes.
This was the reason for the local Dallington Park relay being built, albeit that its a Freeview "light" PSB only transmitter, hence why viewers prefer (where possible) using the Sandy full service transmitter.
That said, check to make sure that any jumper leads used between devices are firmly seated into their sockets, and in cases like this its always best (if possible) to try and check with a neighbour etc to find out if they are also suffering from similar problems with reception, if not, then the problem is liable to be caused by a deficiency in your aerial system, such as water having entered the coax termination box on the actual aerial etc.
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Alistair: Ridsdale is covered by the Caldbeck transmitter located @ 46 miles on a bearing of 235 degrees, albeit with the signal path from that station suffering from a obstruction (minor?) at just under 1mile prior to the village.
A quick check made on the rooftops of properties located in main street of the village showing number of aerials facing towards the Caldbeck transmitter, with only a few facing towards Chatton @ 29 miles / 25 degrees, the signal path from the latter suffering from multiple obstructions from around 9 miles or so.
The channels used by the Caldbeck transmitter being as follows:
BBC1 (C25) - ITV (C28) - Main HD service (C30) - SDN / ITV3 etc (C23) - Pick TV etc (C26) - 4Music etc (C29) - COM7 HD / (C32)
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David Rose: The symptoms as described are suggestive of a fault having developed on your dish system, such as it having moved slightly out of alignment, if you can access the dish? make sure that the bracket its mounted on hasn't slackened off.
Another reason for the problem can caused by water having entered the "F" connector that's screwed into the LNB mounted on the end of the dish arm, this having to be checked by unscrewing the connector from the LNB then further unscrewing it from the coax cable, if all appears to be OK placing a small blob of Vaseline inside the connector before screwing it back onto the coax etc, making sure whilst doing so that none of the strands of the braiding have accidentally become wrapped around the centre core of the coax.
If the "F" connector can eliminated from the equation, then the problem could be down to the box having developed an internal power supply problem, not exactly uncommon on older boxes, a test that "sometimes" works being to disconnect it from the mains for 10 minutes to allow it to cool down before reconnecting it again and allowing it to go through the usual searching for listings procedure, should this restore the box into normal operation then the power supply is defective.
As far as the possible alignment problem is concerned, if at all possible, its a lot less hassle to either try another box on your dish system or alternatively your box on someone else's.
By the way, should you be referring to a Sky+ type of box? try swapping the two LNB input leads over, if the signal returns then the coax that was previously connected into LNB1 is defective.
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Derek Hughes: A Log periodic aerial used (if necessary) in conjunction with a variable gain booster is a far better bet for DTT reception over what you have looking at. However Winter Hill covers a large area, therefore in order to check your reception possibilities a more precise location is required, this in the form of a post code or one from nearby, e.g: a shop / Post office etc.
You may also find the undermentioned link to be of interest.
Best aerial for indoor outdoor motorhome or caravan log periodic
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David Rose : That said was on the assumption that it is "not" snowing where you are located? or if it is, that the problem occurred before it started?, because should it not have, then the no signal problem can be caused by a build up of snow on the either the dish or the face of the LNB, carefully drawing a brush across both mentioned usually curing the problem.
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Derek Hazell: Provided that the Freeview box in the kitchen is fed from a separate outlet from the booster to that used by the TV in the living room, then the problem is likely to be caused by the Freeview boxes tuner being less sensitive to the type fitted in the TV.
If though its sharing the outlet used by the TV, temporarily connect the box into the socket used by the TV and check if the ITV programmes have returned, that is provided that you haven't already retuned the box? if you have, then you will have to carry out another retune to recover the channels.
Should the second situation apply, then you will have to purchase a two way powered splitter to rectify the problem on a permanent basis, one outlet feeding the living room TV, and with the other the Freeview box in the kitchen, the splitters common input fed from the booster outlet.
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Friday 19 December 2014 4:39PM
MRS B MURTHA: Indications seen on reception predictor are that your area is not particular favourable as far as Freeview reception is concerned, the location in question being covered by the Overstrand Freeview "light" PSB only transmitter located @ 0.5 miles away on a bearing of 129 degrees, the Freeview "light" service offering a somewhat restricted range of programme channels by "not" transmitting the full range of commercial channels available from main stations, e.g: (10) ITV3 / (20) Drama / (11) Pick TV etc / (18) 4Music, as reception predictors are not by their very nature 100% accurate, can you confirm (or otherwise) that the aforementioned programme channels are "not" receivable on "Freeview".
However, the BBC services should be in both the lounge and bedroom, therefore if its OK in the lounge but not the bedroom then the question has to be, do you have a socket in the bedroom? or is it supplied via some form of extension lead from the lounge?, or are you trying one of those "same room" type of aerials? as these devices are totally unsuitable for use in areas such as yours.
Also, you mention having limited aerial feeds in the property but that you can get Sky, is there a Sky outlet socket in the bedroom? this identified by a threaded stub protruding from a wall mounted outlet point.
Further advice dependant on feedback.